eqn

, neqn

, checkeq

- typeset mathematics test

Synopsis

eqn [-dxy] [ -fn] [-pn] [ -sn] [file]...

neqn [file]...

checkeq [file]...

Description

eqn and neqn are language processors to assist in describing equations. eqn is
a preprocessor for troff(1) and is intended for devices that can print troff's
output. neqn is a preprocessor for nroff(1) and is intended for use with terminals.
Usage is almost always:

example% eqn file ... | troff
example% neqn file ... | nroff

If no files are specified, eqn and neqn read from the standard
input. A line beginning with .EQ marks the start of an equation. The
end of an equation is marked by a line beginning with .EN. Neither
of these lines is altered, so they may be defined in macro packages
to get centering, numbering, and so on. It is also possible to
set two characters as ``delimiters''; subsequent text between delimiters is also treated as
eqn input.

checkeq reports missing or unbalanced delimiters and .EQ/.EN pairs.

Options

The following options are supported:

-dxy

Sets equation delimiters set to characters x and y with the command-line argument. The more common way to do this is with delim xy between .EQ and .EN. The left and right delimiters may be identical. Delimiters are turned off by delimoff appearing in the text. All text that is neither between delimiters nor between .EQ and .EN is passed through untouched.

-fn

Changes font to n globally in the document. The font can also be changed globally in the body of the document by using the gfont n directive, where n is the font specification.

-pn

Reduces subscripts and superscripts by n point sizes from the previous size. In the absence of the -p option, subscripts and superscripts are reduced by 3 point sizes from the previous size.

-sn

Changes point size to n globally in the document. The point size can also be changed globally in the body of the document by using the gsize n directive, where n is the point size.

Operands

The following operands are supported:

file

The nroff or troff file processed by eqn or neqn.

EQN LANGUAGE

The nroff version of this description depicts the output of neqn
to the terminal screen exactly as neqn is able to display it. To
see an accurate depiction of the output, view the printed version of this
page.

Tokens within eqn are separated by braces, double quotes, tildes, circumflexes, SPACE, TAB, or
NEWLINE characters. Braces { } are used for grouping. Generally speaking, anywhere a single
character like x could appear, a complicated construction enclosed in braces may be
used instead. A tilde (~) represents a full SPACE in the output; a circumflex
(^) half as much.

Subscripts and superscripts:

These are produced with the keywords sub and sup.

x sub i

makes

a sub i sup 2

produces

e sup {x sup 2 + y sup 2}

gives

Fractions:

Fractions are made with over.

a over b

yields

Square Roots:

These are made with sqrt

1 over sqrt {ax sup 2 +bx+c}

results in

Limits:

The keywords from and to introduce lower and upper limits on arbitrary things:

lim from {n→ inf } sum from 0 to n x sub i

makes

Brackets and Braces:

Left and right brackets, braces, and the like, of the right height are made with left and right.

left [ x sup 2 + y sup 2 over alpha right ] ~=~1

produces

The right clause is optional. Legal characters after left and right are braces, brackets, bars, c and f for ceiling and floor, and "" for nothing at all (useful for a right-side-only bracket).

Vertical piles:

Vertical piles of things are made with pile, lpile, cpile, and rpile.

pile {a above b above c}

produces

There can be an arbitrary number of elements in a pile. lpile left-justifies, pile and cpile center, with different vertical spacing, and rpile right justifies.

Sizes and font can be changed with sizen or size±n,roman, italic, bold, and fontn. Size and fonts can be changed globally in a document by gsizen and gfontn, or by the command-line arguments -sn and -fn.

Successive display arguments:

Successive display arguments can be lined up. Place mark before the desired lineup point in the first equation; place lineup at the place that is to line up vertically in subsequent equations.

Shorthands:

Shorthands may be defined or existing keywords redefined with define:

define thing % replacement %

Defines a new token called thing which will be replaced by replacement whenever it appears thereafter. The % may be any character that does not occur in replacement.

Keywords and Shorthands:

Keywords like sumintinf and shorthands like >=→ and != are recognized.

Greek letters:

Greek letters are spelled out in the desired case, as in alpha or GAMMA.

Mathematical words:

Mathematical words like sin, cos, and log are made Roman automatically.

troff(1) four-character escapes like \(bu (·) can be used anywhere. Strings enclosed in
double quotes ". . ." are passed through untouched; this permits keywords to be entered as
text, and can be used to communicate with troff when all else fails.